1. Field of Invention
This invention relates to a recorder for performing recording operation on a recording paper in response to measured input signals.
2. Description of Prior Art
Recorders which use microprocessors are known. One example is disclosed in U.S. Pat. No. 4,433,338. In these prior recorders which record data on a recording paper, recording precision cannot be maintained when the recording paper is changed in dimension, such as extension or contract which occur with changes in ambient humidity. Prior art recorders have not dealt with this problem and hence recording precision is not continuously maintained. U.S. Pat. No. 4,433,338 does not deal extensively with this problem nor correct adverse effects resulting from for example expansions and contractions of the recording paper.
Moreover, prior art ordinary recorders are further deficient in that although they are sufficient for steady state recording or event recording alone, because of their mutually exclusive purposes, they have heretofore never been combined in one apparatus to perform both functions.
The prior art steady state recorders are usually sufficient to perform recording operation for a long sampling period because they are used mainly for recording and monitoring occurences which are not changed very substantially in a steady state.
On the other hand, an event recorder is used when the recording changes are substantial, such as occurence of disorder in a system, to make records before and after the timing, which timing is for a short sampling period, so that the records may be used for fine operation analysis. The event recorder requires a memory for storing a considerable amount of data because the data before and after an event are to be recorded, or are outputted upon operator request.
The ordinary steady state recorder does not need a memory because it is sufficient to output the sampled data at each sampling instant. Since these two types of recorders have different intended purposes and required functions, heretofore, they have usually been positioned as different and independent, separate devices.
Generally, the input signals to be recorded in the event recorder are so important that they have to be frequently recorded and monitored, as usual, also in the steady state. Thus, heretofore, it was the practice to input an input signal commonly and in parallel to both the steady state recorder and the event recorder. That is to say, two separate recorders were both accessed in parallel. This practice, of course, was disadvantageous since the cost was at least two fold, the power requirements were two fold, and possibility of breakdown increased. Furthermore, the recording format characteristics for the steady state recorder and the event recorder are frequently different and often mutually exclusive, so as to require different recording criteria for both the steady state and event recording. Furthermore, such different recording criteria cannot be accurately and quickly determined.
It would be advantageous to perform event and steady state recording on a common recording paper through a switching technique. The prior art, including U.S. Pat. No. 4,433,338, is deficient on this point.
Moreover, it is desirable to prevent the continuity of recording of steady state data from being interrupted and the steady state data from being lost by recording of the event.